VICTORY CIGAR? Roberto Castro (inset) has The Players Championship field chasing him after posting a first-round 63 to tie a course record, leaving a group of players including Tiger Woods (pictured) and Rory McIlroy three-plus shots behind. Photo: Getty Images (2)

PONTE VEDRA BEACH, Fla. — Rory McIlroy entered this week’s Players Championship having played the tournament three times and never having made a cut nor shooting a round under par. In his six rounds, McIlroy’s best scores were two even-par 72s.

Thursday, McIlroy obliterated that personal record in the opening round with a 6-under 66 to stand just three shots out of the lead and seemingly a lock to make his first cut at the TPC-Sawgrass.

“It’s my first round under par on this golf course, so I’ll take anything I can get,’’ McIlroy said.

McIlroy said a key to his success was a new-found patience on the Stadium Course, where he used driver on just three holes (11, 14 and 16).

“[On] this course it is just about getting your ball in play,” he said. “Once you do that … the way I feel like I’m hitting my irons, I can take advantage of that.’’

* Jason Dufner holed out his second shot from 158 yards on the 18th. The eagle was only the third in Players Championship history on the 18th. Carlos Franco had the last one, in 2002, and Glenn Day had one in 1998.

Michael Thompson aced the eighth hole with a 3-iron.

* Leader Roberto Castro, making his first start at The Players Championship, is trying to become only the fourth player to win the event in his first try, joining Jack Nicklaus (1974), Hal Sutton (1983) and Craig Perks (2002).

* Scott Langley, who had been bumped from the field when Derek Ernst won on Sunday at Quail Hollow to get into The Players Championship, got into the tournament as the first alternate when Bob Estes withdrew. Langley, who practiced all week in hopes of getting into the field, shot 76 while Ernst shot 74.

Langley, who had never been to the TPC-Sawgrass before this week, said, “I came here knowing Derek had won and I was first alternate, so I just tried to get ready as if I were in the tournament. You really never know.’’

Langley said on Wednesday he was “hoping to get a phone call.’’ He insisted he had not hard feelings for Ernst, saying, “My first reaction was I was very happy for him, being a fellow rookie. The second though was of course I was bummed to be bumped out, but you can’t blame a guy for playing well. That’s golf.

“The responsibility falls on my shoulders to play better so I could have secured my spot a little better.’’

Before he knew he was in the field, Langley said jokingly, “If I don’t get in, [Ernst] owes me something. I’ll just figure out what that is over the next couple weeks.’’

Ernst said winning Wells Fargo gave him “mixed emotions’’ knowing it might knock his friend out of The Players.

* One of the odd rounds of the day came from Scott Stallings, who carded seven birdies yet finished just 1-under thanks to a double bogey on No. 12 and a triple on 16 leaving him with 40 on the back nine.

“It just goes to show about the golf course and how volatile it is,’’ Stallings said.